Study On Upgrade And Transformation Design Of PTA Wastewater Treatment Process

With the continuous development of my country's petrochemical industry,the production of purified terephthalic acid(PTA)as an important petrochemical raw material has also increased year by year,and its wastewater discharge has also increased year by year.At present,the PTA wastewater using traditional treatment processes implements the secondary standard of the comprehensive discharge standard.However,as the country controls the discharge of industrial enterprises more and more stringently,and the recycling of water resources is also paid more and more attention,therefore,how to achieve a large number of PTA after treatment,wastewater reaches higher discharge standards and the recycling of water resources has become a problem that needs to be solved urgently by petrochemical companies.This paper,taking a petrochemical co.,LTD.,the existing domestic PTA production wastewater as the research target,through the investigation and comparison,the upgrade of the original wastewater treatment process are proposed,with reverse osmosis technology for waste water desalination process,with ultrafiltration unit as the reverse osmosis pretreatment process,made the “pretreatment + ultrafiltration,reverse osmosis membrane separation” give priority to the transformation process,the effluent water quality meet the water quality standard of reclaimed water used as “The reuse of urban recycling water-Water quality standard for industrial use”(GBT19923-2005),the quality of a small part of the external drainage meets the level I discharge standard of “the Integrated Wastewater Discharge Standard”(GB8978-1996).The ultrafiltration membrane is Dow's DOWTM ultrafiltration membrane(IMT10060 UF/MB/G),which adopts the external pressure type water inlet method,making the ultrafiltration membrane relatively difficult to block.After transformation,the average net water production of the ultrafiltration membrane is 300 m3/h,the water recovery rate is 88%,and the running membrane flux is 35 L/m2·h.After ultrafiltration treatment,the suspended solids and turbidity of the discharged water decreased significantly,and the requirements of reverse osmosis inlet water pretreatment were met.The reverse osmosis unit adopts Dow's FILMTECTM reverse osmosis membrane.The arrangement structure of reverse osmosis is designed as a first-stage two-stage type.Its treatment water volume is 300 m3/h,the recovery rate is 70%,the desalination rate is 95%,and the average membrane,the flux is 16.0 L/m2·h.Aiming at the problem of membrane fouling,the membrane cleaning method was determined through demonstration analysis,and suggestions for long-term operation and maintenance of the membrane unit were proposed.On this basis,the main equipment,dosage and cleaning frequency of the new process were designed and calculated,and relevant design drawings were completed.